Field of the Invention
The present invention relates to a device for cooling a brain of a living body.
Description of the Background Art
If a living body, including a human body, enters a state where the respiratory functions and the circulatory functions are incompetent, such as cardiac arrest (hereafter “cardiac arrest state”), oxygen supply to the brain becomes insufficient. It is known that this lack of oxygen supply destroys brain cells, that is, causes ischemic neuronal damage.
Artificial respiration and other cardiac resuscitation treatments can be performed on a living body in the cardiac arrest state. However even if the living body is resuscitated from the cardiac arrest state by these treatments, a mentioned ischemic neuronal damage may give a sequela to the brain.
With the foregoing in view, recently a so called “hypothermic therapy” is proposed as a treatment for preventing the ischemic neuronal damage from being caused. In hypothermic therapy, the brain is cooled by lowering the body temperature of the living body in the cardiac arrest state.
As an example of a device for performing hypothermic therapy, a brain cooling device disclosed in Japanese Patent Application Laid-Open No. 2007-75505 is known. This cooling device has a cuff which can be disposed in an esophagus of the living body by oral or transnasal insertion, a tube connected to the cuff, and a port connected to the tube on the opposite side of the cuff. The cuff is expanded by injecting cooled fluid into the cuff via the tube in a state where the cuff is disposed in the esophagus of the living body. Thereby the cuff closely contacts the inner wall of the esophagus. As a result, the blood in the blood vessels (carotid arteries) that are located near the inner wall of the esophagus and supply blood to the brain is cooled down, and therefore the brain is cooled down.
The cooling device according to Japanese Patent Application Laid-Open No. 2007-75505 has a tube for supplying the cooled fluid to the cuff (hereafter called “supply tube”), and a tube for draining the fluid from the cuff (hereafter called “drain tube”) individually.
In the case of cooling the brain using the cooling device of Japanese Patent Application Laid-Open No. 2007-75505, it is preferable to circulate the fluid as follows, in terms of increasing heat exchange efficiency. That is, the cooled fluid is supplied into the cuff via the supply tube which is guided to the outside of the living body, and the fluid drained from the cuff via the drain tube which is guided to the outside of the living body, is cooled down, and the fluid is circulated back to the cuff again.
In the case of the cooling device of Japanese Patent Application Laid-Open No. 2007-75505, the cuff must be closely contacted with the esophagus of the living body to cool down the brain, but if this close contact is too vigorous and the pressure of the fluid in the cuff becomes too high, burden on the inner wall of the esophagus and on the cuff itself increases. Hence the fluid in the cuff must be maintained at an appropriate level. However holding the pressure of the fluid in the cuff at an appropriate level is not easy, since this circulation is manually performed by a medical staff.